1. Field of the Invention
The present invention relates to a recording apparatus for use as an information output apparatus for a word processor or a personal computer or an image forming apparatus such as a copying machine or a facsimile apparatus, and more particularly to a recording apparatus for recording information by discharging ink droplets to a recording medium in accordance with information to be recorded.
2. Related Art
In recent years, so-called ink jet recording apparatuses (ink jet printers) for recording information by discharging liquid ink to a recording medium in accordance with information to be recorded have been used widely because of high quality recorded results, high recording speed, excellent adaptability to a variety of recording sheets and low noise.
Ink to be used in the ink jet recording apparatus usually contains water soluble dye or pigment, the ink discharged to a recording sheet being then allowed to penetrate and be absorbed by the recording sheet and the solvent of the ink being then evaporated so that the ink is fixed.
The fixing process takes a time which is determined by the type of the ink, the recording density, the type of the recording sheet, and the environment, such as the temperature and the humidity.
Therefore, if information is, on a hot and wet day, recorded at a high recording density on a recording sheet, such as a transparent sheet for an overhead projector (OHP), which does not considerably absorb the ink, an excessively long time is required to fix the ink. As a result, if a plurality of sheets are recorded, the recorded second and third sheets are discharged onto the previous recording sheet recorded and discharged from the recording portion, thus causing the recording surfaces, which have not been fixed, to be brought into contact with the other sheets. Thus, the recording surfaces are rubbed and bleeding occurs. Furthermore, ink adheres to another sheet, as a result of which the sheet is contaminated or so-called smear takes place.
Also in a case where a member for guiding the recording sheet, which comes in contact with the recording surface of the recording sheet, is disposed from the recording portion to the discharge port for the recording sheet, similar smear takes place.
To prevent occurrence of the smear, a variety of methods have been disclosed, for example, a method using a heater for heating the recording sheet to enhance fixation of the ink, a method in which the recording density is detected to delay the discharge of the sheet for a predetermined time if the density is too high, and a method in which a means for setting a predetermined delay time during the recording operation is provided.
There arises a desire for a recording apparatus, and more particularly, a great desire arises for recording information on a variety of recording sheets.
Recently, postcards of a type having a photograph sheet thereon formed by applying a photograph sheet to the reverse side of a postcard have been put into practical use.
Although the postcard having a photograph sheet thereon has been too thick to be recorded by a conventional recording apparatus, recording can be performed by improving the mechanism for feeding the recording sheet.
However, if an ink jet recording apparatus continuously records a plurality of postcards, each having a photograph sheet thereon, continuous recording of a plurality of the postcards results in the recorded postcards being stacked in the discharge portion of the recording apparatus. As a result, the recording surface of the first postcard and the surface of the photograph sheet on the second postcard are brought into contact with each other or the recording surface of the second postcard and the surface of the photograph sheet on the first postcard are brought into contact with each other. Thus, the foregoing problem of smear generation and other problems will arise.
In addition to the known smear, such as bleeding and contamination of the recorded image, another problem was confirmed that a solvent evaporating from the ink absorbed by the recording surface of a recording medium is absorbed by the surface of a photographic emulsion surface of a silver salt photograph forming a photograph sheet that is in contact with the foregoing recording surface, causing the surface of the photograph sheet to be softened and adhesion to take place between the photograph sheet and the recording surface.
The foregoing problem of adhesion cannot be overcome by the conventional methods of preventing the smear. The reason for this is that, even if the ink has been absorbed by the recording sheet and fixed to a degree that does not generate the smear, evaporation of the solvent from the ink absorbed by the recording sheet is further performed.
A recording sheet of a type formed by applying glue of the same type that is used for postcards to the reverse side of the recording sheet may be employed in the form of a seal. Also the recording sheet of the foregoing type will raise a similar problem to that experienced with the postcard having a photograph sheet.
More particularly, the foregoing method of preventing smear has been established in consideration of the condition of the recording surface to which ink has been discharged but the method is not established in consideration of the surface of the recording sheet that comes in contact with the recording surface. Therefore, the foregoing adhesion phenomenon occurring due to the state of the surface of the recording sheet that comes in contact with the foregoing recording surface cannot be prevented.